It would be good practice to change it.

Unless you have added water to it in the interim (thus diluting the glycol %) it will likely have similar anti-freeze properties to when it was new. In that sense, you won't have to worry about it freezing. If you have added water to it in the interim, that changes the situation. A garage can test it in minuters to tell you what temperature it is good to.

Apart from the above, what coolant has in it are other additives that extend the life of your cooling system components. Those additives get depleted over time. The reason for changing the fluid is to minimize the cost of replacing water pumps, radiators, and so on, due to running ineffective coolant.

At times, coolant has been called 2 year, 4 year, and lifetime. With modern BMW coolant, I go 4 years. There isn't a downside to changing it, apart from the expense, and I believe I will come out ahead by not having to change water pumps, etc, early.

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2007 X3 3.0si, 6 MT, Premium, White

Retired:
2008 535i, 6 MT, M Sport, Premium, Space Grey
2003 X5 3.0 Steptronic, Premium, Titanium Silver
2002 325xi 5 MT, Steel Grey
2004 Z4 3.0 Premium, Sport, SMG, Maldives Blue