In the customers sheet you need to include a VLOOKUP formula in each of the columns for match the member name to the date joined in the sheet for that particular year. You can use absolute (with $ signs) references to the look up ranges and offset and relative reference to the member name so that the formulas can be copied down the columns for all members.
In the VLOOKUP formula, use FALSE for the fourth option at the end to return exact matches (TRUE finds the closest match). In this case you may also want to wrap the formula in an IF function to filter out results where a match is not found.
