If you are a similar age to me and passed your test in the same era as me (the 1970s) you will have B+E, C1, and C1+E through "grandfather rights". These will (at least should) endure as long as you have a licence, so as you start to have to renew periodically and self-certify fitness you should keep these automatically. The C1 category is the one that allows you to drive up to 7.1/2 ton vehicles, which used to be allowed on the standard "car licence".
If, like me, you also have C and C+E as vocational categories, i.e., you did the HGV test, you will need to renew then every 5 years from (I think) age 45 and annually from 65. To renew, you need a medical certifice from a GP. They will not renew automatically.
I am told (and perhaps someone here can confirm) that if you do not renew your C/C+E and allow them to lapse, you can reactivate them later, after the lapse, by getting a medical and reapplying without the need for any testing etc.